Sulfur-oil slurry preparation for pipeline transportation

ABSTRACT

AN IMPROVED METHOD OF PREPARING A SULFUR-OIL SLURRY FOR PIPELINE TRANSPORTATION USING A SHROUDED NOZZLE FOR INJECTION OF MOLTEN SULFUR INTO OIL TO FORM THE SLURRY.   D R A W I N G

C. J. KUHRE SULFUR-OIL SLURRY PREPARATION FOR PIPELINE TRANSPORTATION Filed April '7, 197C 2 Sheets-Sheet 1v BUTANE I6 COMPRESSOR 8: CONDENSER [DRAFT TUBE VAPOR MOLTEN SULFUR l2 ADDITIVE STEAM STEAM CONDENSATE SULFUR SLURRY FIG.

INVENTORS:

C. J. KUHRE FIG. 2

c.c. SEGERSTROM Win/p THElmGENT May 16, 1972 c J KUHRE ETAL 3,663,478

SULFUR-01b .SLUHRY PREPARATION FOR PIPELINE 'LRANSPORTATION Filed April 7, 1297c 2 Sheets-Sheet 2 MOLTEN 3 30 SULFUR IN 1 32 IH I; E THERMOWELL CONDENSATE STEAM IN i L [34 32 Z PURGE GAS 5 miss 36 3a OIL m 37 FIG- 3 FIG. 4

BY; WM)

THEIR AGE NT 3,663,478 SULFUR-OIL SLURRY PREPARATION FOR PHELINE TRANSPORTATION Calvin J. Kuhre, Kensington, and Clifford C. Segerstrom, Lafayette, Calif., assignors to Shell Oil Company, New York, N.Y.

Filed Apr. 7, 1970, Ser. No. 26,278 Int. Cl. Blj 13/00 US. Cl. 252-314 7 Claims ABSTRACT OF THE DISCLOSURE An improved method of preparing a sulfur-oil slurry for pipeline transportation using a shrouded nozzle for injection of molten sulfur into oil to form the slurry.

The present invention relates to an improved method for preparing sulfur-oil slurries for pipeline transportation over great distances.

BACKGROUND OF THE INVENTION The transportation of sulfur neat or as a water or oil slurry in pipelines is well known in the art as noted by reference to U.S. Pat. 2,798,772; 2,917,345; 2,947,578 or 3,476,411. In making a sulfur-hydrocarbon slurry, the sulfur is generally sprayed or dispersed in molten form into either water or a hydrocarbon to form a slurry suitable for transportation through a pipeline. Formation of a stable slurry wherein the sulfur does not undergo any undesirable change or the slurry does not exhibit a tendency to wide variation in viscosity is essential to the process in addition to other problems which may be encountered during and after transportation of the slurry through a pipeline. Thus, attrition, agglomeration and separation of the sulfur from the carrier fluid; plating, depositing or coating of the sulfur on pipeline walls causing plugging of the pipeline and corrosion; viscosity changes in the slurry due to pressure and temperature variations requiring greater pumping power which increases operation costs; etc., are only a few of the problems normally encountered in transporting sulfur-liquid hydrocarbon slurries through pipelines.

Although the above are serious problems for consideration in transporting sulfur through pipelines, nevertheless the transportation of sulfur in slurry form through pipelines can be made to be an effective, attractive and economic means of sulfur transportation, particularly since sulfur is recovered or obtained from isolated, remote and inaccessible areas, and must be transported to desired accessible areas. As noted above, a number of methods have been proposed for pipeline transportation for sulfur slurries such as injecting molten sulfur into water or a liquid hydrocarbon thereby forming a sulfur slurry for pipeline transportation. These methods for making sulfur slurries suitable for transporting through pipelines generally do not overcome the agglomeration, deposition, sticking, coating and/or plugging problems described above. Various means have been proposed such as temperature control means or addition to the oil of anti-agglomerants, corrosion inhibitors, e.g., asphaltenes and the like as described in copending applications Ser. No. 820,012, filed Apr. 28, 1969, or Ser. No. 784,925, filed Dec. 18, 1968, now US. Pat. No. 3,582,147, Ser. No. 813,994, filed Apr. 4, 1969, now US Pat. No. 3,547,497, Ser. No. 784,616, filed Dec. 18, 1969, now US. Pat. No. 3,532,389, or Ser. No. 784,- 727, filed Dec. 18, 1969, now US. Pat. No. 3,547,495.

SUMMARY OF THE INVENTION It has now been discovered that an improved method of 3,663,478 Patented May 16, 1972 preparing a sulfur-oil slurry which results in spherical particles of controlled dimensions such as 10 to 500 microns and preferably between 30 and 350 microns and which are resistant to agglomeration, sticking, etc., and is particularly suitable for pipeline transportation by utilizing a shrouded or shielded nozzle having means for injecting molten sulfur and optionally having means within the shroud or shield for injecting oil so that the molten sulfur and optional oil do not come in direct contact with the oil in the slurry vessel used for making the slurry. The shrouded nozzle can be submerged in the oil or above it. It has been found that by means of a shrouded nozzle, sulfur plugging normally caused when using conventional spraying means is obviated and that by use of shrouded or shielded nozzle the size and shape of the sulfur particles formed when molten sulfur is sprayed into oil are so controlled as to give spherical particles of 10 to 500 microns without recourse to chemical or other means.

Instead of a single shrouded nozzle, a series of such shrouded nozzles can be used and positioned strategically in the slurry vessel and the injection can be positioned and directed downwards, horizontally or upwards or any combination desired.

One of the main functions of the shroud is to promote initial contact of the sulfur with fresh oil, i.e., oil which has not previously contacted molten sulfur. It has been found that fresh oil is much more effective in promoting spherical, non-agglomerated particles than oil which has already been exposed to molten sulfur and shrouded nozzles and in contacting molten sulfur with fresh oil. Oil which is unsuitable for slurrying sulfur can be doped or treated with asphaltenes and then can be directed into the shroud surounding the sulfur as non-agglomerated spheres.

Also, shrouded nozzles help prevent sulfur from freezing in the nozzle on shut downs, flow interruptions or the like.

A particular embodiment of the invention is illustrated in the accompanying drawings in which FIGS. 1 and 3 show a sulfur-oil slurry system in which the shrouded nozzle through which molten sulfur is sprayed into the oil to form the slurry. FIGS. 2 and 4, respectively, are detailed drawings of shrouded nozzles or systems which can be utilized in the practice of the present invention.

Referring to FIG. 1, oil from line 11 is conducted via line 15 into the slurry vessel and optionally some of the oil from line 11 can be directed through the shrouded nozzle 22 by controlling valve means in line 11. Additives such as corrosion inhibitors, anti-agglomerants, e.g., asphaltenes, etc., if used, can be added to the oil through line 12. Molten sulfur via line 10 is introduced into the oil through shrouded nozzle 22 which can be over or submerged in the oil. To control the slurry temperature at its optimum for preparation of a stable slurry, a vaporizable hydrocarbon, such as butane, can be injected into the slurry vessel via line 16 and escaping vapors can be removed via line 17, recondensed and compressed in 18 and reinjected into line 16. The slurry vessel can be steam jacketed 13 and condensed steam removed via line 19. The slurry during its preparation is agitated by means of a stirrer 14 and within the vessel are draft tubes 20 to effect better slurrying. The finished sulfur-oil slurry is removed from the slurry vessel via line 21.

FIG. 3 is a modification of a slurry vessel as shown in FIG. 1 wherein oil is introduced into the slurry vessel 49 via line 46 having baffles surrounding the nozzle structure 38 through which structure is introduced molten sulfur via line 30 which contains a nozzle as shown in FIG. 4 and is thermally insulated by a steam jacket having inlet line 31 and outlet line 32 and a thermowcll 33' so at to keep the sulfur in a molten state when it contacts the oil and does not condense and plug the system. The slurry vessel contains agitating means 48 and the sulfur-oil slurry is removed via line 50.

FIG. 2 is a detailed drawing of shrouded nozzle 22 of FIG. 1 having tube connection 23 to which is attached shroud 25 having flow holes 27 and nozzle 26. Oil from line 11 has a section 24 which is attached to shroud 25 and wherein molten sulfur from nozzle 26 and oil from 24 are admixed and thereafter admixed with oil into the slurry vessel.

FIG. 4 is a detailed drawing of nozzle 44 which has a long tube 30 through which molten sulfur flows and is kept molten in the line by means of steam lines 31 and 32 and thermowell 33. The nozzle is shrouded by 42 to which is connected a baffle 41 having connected thereto oil line 46 passing into the slurry vessel at 47 and opening at 45 into the slurry vessel. In FIG. 4, numerals 3'4, 35 and 37-43 are structural limitations which are self-explanatory.

Connection 36 is provided for a purge stream of inert gas such as nitrogen. This gas fills the inner shroud 42 and and prevents oil from contacting the sulfur-nozzle end 44 and the steam jacket 43. This in turn prevents freezing of sulfur in the nozzle end in the event of sulfur flow interruptions or shut downs, etc. The sulfur jet passes through the gas space in the inner shroud or cylindrical bafll 41. This feature overcomes the difficulties experience in starting or stopping in a submerged nozzle without such a gas chamber separating the nozzle from direct contact with the oil.

The essence of the present invention is the use of shrouded or shielded nozzles for introducing molten sulfur into oil during the preparation of sulfur-oil slurries thereby preventing nozzle plugging, agglomeration, sulfur settling and separation and the like and producing a stable slurry having a high sulfur concentration of at least 30% and higher, generally above 40% and as high as 60% and in which the sulfur particles are of essentially spherical shape and controlled dimensions.

In the employment of shrouded nozzles in the sulfur-oil slurry preparation in accordance with the teaching of the present invention, cooling of the slurry during its preparation can be effected by use of vaporizable low-molecular weight hydrocarbons such as propane, butane, etc., as described in copending application Ser. No. 784,727, now U.S. Pat. No. 3,547,495, or agglomeration prevented by addition of anti-agglomerants as described in copending applications Ser. No. 820,012 and Ser. No. 784,925, now U.S. Pat. No. 3,582,147, such as asphaltenes and the like.

The utilization of a shrouded or shielded nozzle or device in sulfur-oil slurry preparation not only is an effective means of preventing clogging of the slurry preparation system but effects a most efiicient means for contacting molten slurry and oil without causing agglomeration and sticking and clogging of the system and prevents the formation of an ineffective and unstable slurry system.

The illustrations show two types of shrouded or shielded nozzles which can be used in making slurries of this invention but modifications can be made to suit particular types of oils, additives and slurry conditions to be employed which is best suited for certain specific conditions and therefore shielded nozzles are described in U.S. Pat. 3,285,712 or 3,363,839 or 3,363,843 or 3,408,007 or D.A.S. 1,626,313 and 1,626,312 and the like, can be also used. Also the molten sulfur can be injected into the slurry vessel via a shrouded nozzled downward or upward depending on the conditions best suited for the particular circumstances encountered.

PREFERRED EMBODIMENT Molten sulfur from line 10, FIG. 1, at 120160 F. was injected via shrouded nozzle 22 into a slurry steam jacketed vessel 13 containing crude oil sprayed therein via lines 11 and 15. The slurry was agitated by means of stirring device 14 and improved circulation effected by draft tubes 20. A small amount of asphaltens (20-1000 p.p.m.) was added to the slurry via line 12 to inhibit agglomeration and corrosion and a vaporizable hydrocarbon, butane, was injected into the slurry via line 16 to control the slurry temperature to below F. The slurry containing about 40% sulfur was removed via line 21 and injected into a pipeline to transportation to a terminal station.

Sulfur slurries prepared by the process of the present invention can be transported through pipelines over great distances without the danger of sulfur deposition, agglomeration, sticking or plugging of the slurry vessel or pipeline.

At the terminal end of the line the sulfur can be removed from the liquid hydrocarbon by suitable means such as described in U.S. Pat. 2,798,772, and the sulfur purified by methods as described in U.S. Pat. 2,809,885, or as described in the copending patent application Ser. No. 648,507, filed Nov. 20, 1967, now U.S. Pat. No. 3,- 475,272, which comprises treating oil-ontaminated sulfur with an aqueous solution containing a mixture of alkali hydrosulfide and corresponding hydroxide, e.g., ammonium hydrosulfide and ammonium hydroxide or by other suitable means such as sulfur can be recovered from the oil slurry by filtration of molten sulfur and liquidliquid extraction with a hydrocarbon solvent containing 1050% aromatic. Thus, as the receiving terminal, the sulfur slurry can be filtered and washed. The recovered sulfur is then melted and purified by liquid-liquid extraction with an aromatic hydrocarbon such as cumene. Also, if desired, the filtered sulfur can be steam stripped to recover bright yellow sulfur.

The foregoing description of the invention is merely intended to be explanatory thereof. Various changes in the details of the described method may be made within the scope of the appended claims without depending from the spirit of the invention.

We claim as our invention:

1. The method of preparing a slurry of sulfur in an oil carrier comprising injecting into an oil carrier molten sulfur under agitating conditions through a shrouded nozzle which is above the surface of the oil carrier or submerged therein, the shroud portion of the said shroud nozzle preventing the molten sulfur as it is ejected from the nozzle from coming in direct contact with the oil carrier containing dispersed therein sulfur, the sulfur-oil slurry thus formed containing at least 20% sulfur as sulfur particles in the range of 10 to 500 microns.

2. The method of claim 1 wherein fresh oil is injected and admixed with the molten sulfur in the shroud portion of the nozzle.

3. The method of claim 1 wherein the oil used to form the slurry is a crude oil.

4. The method of claim 3 wherein the crude oil contains asphaltenes.

5. The method of claim 1 wherein more than one shrouded nozzle is used to inject molten sulfur into the oil.

6. The method of claim 1 wherein the shrouded nozzle is submerged in the oil.

7. The method of claim 1 wherein the shrouded nozzle is above the surface of the oil.

References Cited UNITED STATES PATENTS RICHARD D. LOVERING, Primary Examiner U.S. Cl. X.R. 

